KR20120031582A - Fabrication of thin film transistor and integrated circuits by spray printing method - Google Patents

Abstract

PURPOSE: A method for manufacturing an electronic circuit and a thin film transistor is provided to spread a large thin film transistor with a simple process and low costs through a spray printing mode. CONSTITUTION: A substrate is prepared. The substrate is located on the upper side of substrate. A roller regularly maintains speed and tension of the substrate. Solution to be spread on the substrate is manufactured. The solution is organic semiconductor coating solution, metallic oxide solution, and high molecule insulator coating solution. A shadow mask is located on the substrate. The manufactured solution is spread on the shadow mask through a spray apparatus. Remaining solvent is evaporated by executing a thermal process after finishing a coating stage.

Description

Fabrication method of thin film transistor and electronic circuit using spray method {Fabrication of thin film transistor and integrated circuits by spray printing method}

The present invention relates to a method of manufacturing a thin film transistor and a method of manufacturing an electronic circuit including the same, and more particularly, forming a semiconductor layer, an insulator layer, a conductive electrode layer coated by a spray method, and stacking them to form a top gate or bottom. A method of manufacturing a thin film transistor in the form of a gate and an electronic circuit including the same.

Recently, researches are being actively conducted to manufacture thin film transistors (hereinafter referred to as TFTs) by a low temperature process in a solution state. The biggest advantage of this manufacturing method is that the thin film can be manufactured at a relatively low manufacturing cost compared to the process of forming the electronic functional thin film based on the conventional vacuum apparatus. Much research is being conducted to utilize the TFT manufactured by the solution process as a logic circuit of a low-cost RFID tag for recognizing an individual article unit that replaces a driving element or a barcode of a next-generation flexible display. In addition, the TFT thus manufactured may be applied to various flexible electronic devices implemented on a polymer substrate.

When manufacturing TFT by the existing process, the photolithographic method is mainly used in the process of forming an electrode or a wiring. In this photolithography method, a conductive film is formed by a conventional film forming method, such as sputtering, plating, or CDD, after which a photosensitive material is applied onto a substrate, and is developed by irradiating with light, and then etching the conductive film in accordance with a resist pattern. The step of forming the electrode or the wiring pattern of the functional thin film. The photolithography method requires extensive equipment such as a vacuum apparatus and complicated processes in forming, patterning, film forming, and etching the thin film. In addition, the material use efficiency is only a few percent, and when the process is terminated, it cannot be reused and disposed of, resulting in high manufacturing costs and a large amount of unnecessary chemical waste.

On the other hand, the method of forming an electrode pattern or a wiring pattern (thin film pattern) on a board | substrate is proposed using the liquid droplet discharge method (so-called inkjet method) which discharges a liquid material from a liquid discharge head in a liquid droplet state. As a reference to this document, Japanese Patent Application Laid-Open No. 2003-317945, where a thin film pattern ink, which is a functional liquid obtained by dispersing conductive fine particles such as metal fine particles or a precursor thereof, is directly pattern-coated on a substrate. After that, heat treatment or laser irradiation is performed to convert the film into a conductive film pattern of a thin film. According to this method, the conventional complicated film forming process, photolithography, and etching process are unnecessary, and the process is greatly simplified, and the amount of raw materials used is small and productivity is improved.

The inkjet printing process is a method of producing a thin film by applying only a small amount of ink to a desired portion through a very small nozzle, so that the ink is applied only to a desired portion, so that the production and value of chemical waste and by-products are higher than those of other printing processes. There is an advantage that can minimize the use of expensive ink.

However, the inkjet process has a relatively slow printing speed and requires a relatively long time for accurate alignment of the inkjet head and the substrate in order to eject ink where desired, so that a high-speed roll-to-roll based continuous process is applied. There is a problem in that it is difficult to realize higher resolution patterning precision only with relatively expensive equipment.

In order to apply the TFT to an ultra-low-cost RFID tag, the manufacturing cost per unit of the device must be maintained at 10 won or less, so the practical application is possible. When manufacturing an RFID tag using a conventional silicon device, a photolithography or various vacuum deposition processes are required. Therefore, there is a disadvantage that too much manufacturing cost.

In order to solve the above problems, the present invention is to provide a method for manufacturing a thin film transistor and an electronic circuit through a spray printing method that can be applied to a large area at a very low cost.

When the TFT is manufactured by the above solution process, the thin film can be patterned through various printing processes. In addition, by implementing this process in a roll-to-roll, it is possible to manufacture the device at a high speed, so that the manufacturing cost can be drastically reduced and the device can be manufactured at a very low cost of less than 10 won.

Japanese Patent Laid-Open No. 2003-317945

None.

Therefore, a main object of the present invention is to provide a method for manufacturing a large area TFT and an electronic circuit by applying a large area of the electronic functional thin film that can be patterned through a spray printing method at a relatively low price.

In addition, in the present invention, the spray coating method is combined with a roll-to-roll based continuous process to apply a large-area electronic functional thin film to a plastic substrate proceeding at a high speed, thereby manufacturing a TFT and an electronic circuit. It is another purpose to provide a way to do it.

Means for Solving the Problems In order to achieve the above object of the present invention, a means for solving the problems is as follows.

Preparing a substrate;

Preparing a solution to be applied to the substrate;

Applying the solution to a substrate via a spray device;

Performing heat treatment after the coating step is completed to evaporate the remaining solvent.

In addition, the present invention to achieve the above object of the invention more specifically

Preparing a substrate;

Preparing a solution to be applied to the substrate;

Placing a shadow mask on a portion of the substrate that requires patterning such as a source / drain electrode;

Applying the solution to a substrate via a spray device;

After the coating step is completed, the heat treatment may be performed to prepare a TFT by evaporating the remaining solvent.

Also,

Positioning the substrate on top of the substrate;

Connecting both ends of the substrate to a take-up roll and a take-up roll;

Continuously moving using a roller while maintaining a constant tension and speed of the substrate portion connected to the take-up roll and the take-up roll;

Spraying a coating liquid from a spray coating part onto a substrate positioned on the continuously moving base part; continuously manufacturing a TFT by a roll-to-roll coating method, comprising: Provide a method.

The present invention has the effect of applying a large area TFT through a very inexpensive process.

1 is a schematic diagram of manufacturing a TFT by applying a semiconductor ink on a substrate provided through a spray printing method.
FIG. 2 is a schematic diagram illustrating a method of forming a pattern by applying a solution only to an open part by applying spray printing on a shadow mask in which a pattern is formed in advance.
3 is a schematic diagram of a bottom gate type TFT.
4 is a schematic diagram of a top gate type TFT.
5 is an optical microscope image of various organic semiconductor thin films applied by spray coating on source / drain electrodes formed through spray coating.
6 shows a transition curve of a P-Channel tip pentacene organic thin film transistor manufactured by spray printing.
Figure 7 shows the transition curve of N-Channel dicyano phenylene dicarboxyl imide prepared by spray printing.
8 is a schematic diagram of a CMOS type inverter in which P-Channel and N-channel are respectively patterned through a spray printing method.
FIG. 9 shows an output curve of a CMOS input inverter made of P-Channel tip pentacene and N-channel dicyano phenylene dicarboxyl imide through a spray printing method.
FIG. 10 shows a gain curve according to a CMOS input voltage made of P-Channel tips pentacene and N-channel dicyano phenylene dicarboxyl imide through a spray printing method.
11 shows a schematic view of a thin film transistor manufacturing process through a roll-to-roll spray printing method.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings and examples.

1 is a schematic diagram of manufacturing a TFT by applying a semiconductor ink on a substrate provided through a spray printing method.

FIG. 2 is a schematic diagram illustrating a method of forming a pattern by applying a solution only to an open part by applying spray printing on a shadow mask in which a pattern is formed in advance.

As shown, the present invention relates to a method of manufacturing a TFT by spraying a solution from a spray coating onto a substrate. The spray coating method is also applicable to the roll-to-roll continuous process.

3 is a schematic diagram of a bottom gate type TFT.

4 is a schematic diagram of a top gate type TFT.

5 is an optical microscope image of various organic semiconductor thin films applied by spray coating on source / drain electrodes formed through spray coating.

In order to manufacture a thin film transistor through a spray method, first, a substrate on which a TFT is to be manufactured must be prepared. Usable substrates include n-type or p-type doped silicon wafers, glass substrates, polyethersulphones, polyacrylates, polyetherimides, polyimides, polyethylene Terephthalate (polyethyeleneterepthalate), polyethylene naphthalate (polyethylene naphthalate) includes a plastic film and an indium tin oxide coated glass substrate and a plastic film, but is not limited thereto. After dissolving the desired material in a suitable concentration in a solvent, it is applied to the substrate through a spray apparatus, and the solvent is evaporated through heat treatment to prepare a thin film in a solid state.

A shadow mask with a desired pattern is placed on a substrate where a pattern is needed, such as a source / drain electrode of a thin film transistor, and a solution is sprayed through a spray device to produce a thin film having a desired pattern through heat treatment.

The organic semiconductor coating liquid used in the present invention is polythiophene and its derivatives, polythiothiothiophene and its derivatives, TIPS pentacene and its derivatives, pentacene precursors (pentacene precursors) ) And its derivatives, alpha-6-thiophene and its derivatives, polyfluorene and its derivatives, pentacene, tetracene, anthracene, perylene and its derivatives , Rubrene and its derivatives, coronene and its derivatives, phenylene tetracarboxylic diimide and its derivatives, polyparaphenylene vinylene and its derivatives, polythiophenevinyl Enes and derivatives thereof, oligothiophenes of alpha-5-thiophenes and derivatives thereof, phthalocyanine and derivatives thereof with or without metals, naphthalene tetracarboxylic acid diimide and Their derivatives, polyphenylene tetra carboxylic diimide-polythiophene copolymer and a derivative thereof (poly (perylene tetracarboxylic diimide) -co- (thiophene)), etc. may be used but is not necessarily limited to this.

The metal oxide coating used in the present invention is selected from oxite oxide mixed with zinc, indium, gallium, tin and the like. More specifically, zinc oxide, indium tin oxide, tin oxide, zinc tin oxide, indium gallium zinc oxide oxide, etc. may be mentioned. However, it is not necessarily limited thereto. The metal oxide ink is formed through a spray method and a thin film is heat-treated at 100 to 600 ° C. to obtain desired semiconductor properties.

In the present invention, a polymer insulating solution is prepared by completely dissolving a material used as an insulating layer in a solvent to form a gate insulating film. The gate insulating film is composed of a single film or a multilayer film of an organic insulating film or an inorganic insulating film capable of a solution process, or an organic-inorganic hybrid film. As the inorganic insulating film, a solution in which nanoparticles such as Al 2 O 3, Ta 2 O 5, BST, and PZT, which can be formed by a solution process, is dispersed, is used, and any one or more selected from among them is used. The organic insulating film may include polymethacrylate (PMMA, polymethylmethacrylate), polystyrene (PS, polystyrene), phenolic polymer, acrylic polymer, imide polymer such as polyimide, arylether polymer, amide polymer, fluorine polymer, p -Use any one or more selected from xyrene-based polymer, vinyl alcohol-based polymer, parylene (parylene).

Apply an insulator solution for forming a gate insulating film prepared in a solution state onto a thin film of an organic semiconductor formed by spray printing to an appropriate thickness capable of sufficiently exhibiting the function of the insulating film, and at least a break point of the solvent to completely evaporate the solvent used. Heating for 10 minutes or more to form a gate insulating film. In addition, a polymer electrolyte-based gel material is used as a gate insulating film through spray coating. In this case, the gate insulating film is present in a gel state and may serve as both the gate insulating film and the gate electrode without forming the gate electrode.

Finally, the gate electrode is formed by spray printing using the conductive ink used to form the source / drain electrodes described above to form the gate electrode. Patterning is attempted using the shadow mask method described above to selectively form a gate electrode only on the active layer of the transistor.

In order to form an electronic circuit such as a CMOS inverter or a ring oscillator through the spray coating method, hole-transfer and electron-transfer semiconductor inks for forming P-Channel and N-Channel are patterned through a shadow mask as shown in FIG. Connect to 1: to manufacture CMOS inverter. The ring oscillator is manufactured by connecting the gate and the drain of the CMOS inverter through a via hole and connected in series.

6 shows a transition curve of a P-Channel tip-pentacene organic thin film transistor manufactured by spray printing.

Tips pentacene is dissolved in a solvent such as toluene, xylene or chlorobenzene at a concentration of 10 mg / ml and sprayed in the spray coating for about 1-10 seconds to obtain a thin film, preferably about 30-200 nm thick. However, the present invention is not necessarily limited thereto, and a person skilled in the art can adjust the injection time and thickness as necessary. Maintain a spacing of 10 – 30 cm between the substrate and the spray jet nozzle. The fabricated TIP pentacene thin film transistor showed the characteristics of a typical hole-transfer transistor and its device performance showed 0.1 cm2 / Vs mobility and 15 V threshold voltage.

7 shows a transition curve of an N-Channel dicyano phenylene dicarboxyl imide organic thin film transistor prepared by spray printing.

The method for preparing the disaano phenylene dicarboxyl imide solution for spray printing is very similar to the method for preparing the tips pentacene solution described above, and the solvent used is also the same. The prepared dicyano phenylene dicarboxyl imide thin film transistor showed the characteristics of a typical electron transfer thin film transistor. The measured device characteristics showed a mobility of 0.1 cm2 / Vs and a threshold voltage of -8 V.

8 is a schematic diagram of a CMOS-type inverter in which the P-Channel and the N-channel are respectively patterned through a spray printing method.

In order to realize a CMOS inverter, a pattern in which the source electrode of the P-channel transistor and the drain electrode of the N-channel transistor are combined on the substrate is formed by a photolithography process or inkjet printing process using gold. Place a shadow mask on the formed pattern where only portions of the P-type or N-type transistors are open, respectively, apply only tippentacene on the active layer of the P-Channel transistor, and dicyano phenylene dicarboxylic acid on the active layer of the N-Channel transistor. Demann is applied selectively.

FIG. 9 shows an output curve of a CMOS input inverter made of P-Channel tip pentacene and N-channel dicyano phenylene dicarboxyl imide through a spray printing method. The fabricated CMOS inverter showed stable inverter output curve even at low voltage of 20 volts.

FIG. 10 shows a gain curve according to a CMOS input voltage made of P-Channel tip pentacene and N-channel dicyano phenylene dicarboxylic imide through a spray printing method. The fabricated CMOS inverter showed very high voltage gain of about 20 degrees.

11 is a schematic view of a thin film transistor manufacturing process through a roll-to-roll spray printing method. As shown in the drawing, the roll-to-roll spray printing apparatus includes: a substrate on which a substrate is positioned; A take-up roll and a take-up roll for continuously moving the substrate; A roller for maintaining a constant tension and speed of the substrate;

Located in the upper portion of the base portion is composed of a spray coating unit for spraying a coating liquid on the substrate.

Due to the above configuration, the roll-to-roll spray printing of the present invention places a substrate on an upper portion of a substrate and connects both ends of the substrate to a winding roll and an unrolling roll, and then uses the roller to wind the winding. A continuous printing operation is possible in which the coating liquid is sprayed from the spray coating portion onto a substrate located on the upper portion of the substrate portion while continuously moving while maintaining a constant tension and speed of the substrate portion connected to the roll and the unwinding roll.

Example 1: Manufacture of organic thin film transistor through spray coating method

Glass substrates (Corning Glass, Eagle 2000) were washed in acetone, IP, and distilled water for 10 minutes each by an ultrasonic cleaner and dried by spraying with nitrogen gas to remove impurities on the substrate. The prepared substrate was placed 15 cm under the spray nozzle of the spray coating part, and then dissolves tip pentacene (sigma-aldrich) in toluene in 1% by weight in order to manufacture an organic thin film transistor, and 0.2 microns in order to remove impurities or residues in the solution. The Teflon filter of the meter was used to remove impurities such as undissolved residues and dust. The tip pentacene solution thus prepared is transferred to a reservoir of a spray coater. It was sprayed for 10 seconds in the prepared spray coating.

After spraying the coating solution, the substrate was heat-treated at 120 ° C. for 10 minutes through a hot plate.

[Example 2; Fabrication of Polymer Insulator Thin Film by Spray Coating Method]

Glass substrates (Corning Glass, Eagle 2000) were washed in acetone, IP, and distilled water for 10 minutes each by an ultrasonic cleaner and dried by spraying with nitrogen gas to remove impurities on the substrate. The prepared substrate was placed 15 cm under the spray nozzle of the spray coating part, and then, PMMA, (Sigma Aldrich, molecular weight = 220,000) was dissolved in normal butyl acetate at 8% by weight to prepare a polymer insulator thin film coating solution. The added vial was heated to 80 ° C. for 5 hours. A 0.2 micron Teflon filter was used to remove impurities such as undissolved residues and dust. The MPA solution thus prepared is transferred to a reservoir for spray coating. It was sprayed for 10 seconds in the prepared spray coating. After spraying the coating solution, the substrate was heat-treated at 150 ° C. for 15 minutes using a vacuum oven.

The prepared insulator thin film is heated by heating tungsten filament or boat to aluminum in a high vacuum chamber maintained at a vacuum of 10 ^-6 Torr or lower to vaporize the aluminum, and then vaporize the aluminum through the shadow mask on which the active layer of the transistor is located. Only a thin film was formed thereon, and the thickness of the deposited gate electrode was found to be 15 nm.

Example 3 Metal Oxide Thin Film Transistor Production by Spray Coating Method

Glass substrates (Corning Glass, Eagle 2000) were washed in acetone, IP, and distilled water for 10 minutes each by an ultrasonic cleaner and dried by spraying with nitrogen gas to remove impurities on the substrate. The prepared substrate was placed 15 cm under the spray nozzle of the spray coating part, and then zinc oxide (ZnO) nanoparticles (nano new material) were dissolved in isopropyl alcohol at a concentration of 5.5% by weight, followed by stirring for about 1 hour at a stirring speed of 300 RPM. It was left for 24 hours to completely dissolve. In the same manner as in Examples 1 and 2, in order to remove impurities and residual substances in the solution, impurities such as undissolved residues and dust were removed by using a 0.2 micron Teflon filter. The zinc oxide solution thus prepared was transferred to a reservoir for spray coating and sprayed for 20 seconds on the prepared spray coating. After spraying the coating solution, the substrate was heat treated at 400 ° C. for 1 hour using a vacuum oven.

[Example 4; Manufacturing of CMOS Inverter and Electronic Circuit by Spray Coating Method]

A substrate was prepared as in Example 1 to form N-type and P-type source / drain patterns for an inverter in a CMOS type on the substrate. The shape of the specific pattern is the same as the schematic diagram of FIG. On the prepared pattern, a shadow mask in which only the active layer of the P-type transistor was opened was first placed, and a tip pentacene solution was prepared as in Example 1 above, and then it was applied by spray printing. Thereafter, heat treatment was performed as in Example 1 to remove the remaining solvent. Then, place a shadow mask in which only the active layer of the N-type transistor is opened, prepare a solution of dicyano phenylene dicarboxyl imide as in Example 1, apply it by spray printing, and heat-treat the remaining solvent. It was completely removed.

101: winding roll 102: unwinding roll 103, 104, 105, 106: roller
107: base portion 108: substrate 109: spray coating portion
400 and 500: substrate 410 and 510: gate electrode
420 and 520: gate insulating film 430 and 530: source / drain electrodes
440: electron / hole injection layer 550: organic semiconductor

Claims (18)

Preparing a substrate;
Preparing a solution to be applied to the substrate;
Applying the prepared solution to a substrate through a spray device;
Method of manufacturing a thin film transistor (TFT) through a spray printing method comprising the step of evaporating the remaining solvent by heat treatment after the coating step is finished. Preparing a substrate;
Preparing a solution to be applied to the substrate;
Placing a shadow mask on which the pattern is formed;
Applying the prepared solution to a shadow mask through a spray device;
Method of manufacturing a thin film transistor (TFT) through a spray printing method comprising the step of evaporating the remaining solvent by heat treatment after the coating step is finished. The method of claim 2,
The step of applying the prepared solution to the shadow mask (shadow mask) through a spray device is a method for manufacturing a thin film transistor (TFT) through a spray printing method, characterized in that the coating on only the open part. The method according to any one of claims 1 to 3,
The substrate may be an n-type or p-type doped silicon wafer, glass substrate, polyethersulphone, polyacrylate, polyetherimide, polyimide, polyethylene terephthalate thin film transistor using a spray printing method, characterized in that it is selected from a plastic film selected from the group consisting of polyethyeleneterepthalate, polyethylene naphthalate, a glass substrate coated with indium tin oxide, and a plastic film substrate. How to make (TFT) The method according to any one of claims 1 to 3,
The solution to be applied to the substrate is a method for manufacturing a thin film transistor (TFT) through a spray printing method, characterized in that the organic semiconductor coating liquid, metal oxide coating liquid, polymer insulator coating liquid. The method of claim 5
The organic semiconductor coating liquid may be polythiophene and its derivatives, polythiothiothiophene and its derivatives, TIPS pentacene and its derivatives, pentacene precursors and their derivatives. , Alpha-6-thiophene and its derivatives, polyfluorene and its derivatives, pentacene, tetracene, anthracene, perylene and its derivatives, rubrene ( rubrene) and its derivatives, coronene and its derivatives, phenylene tetracarboxylic diimide and its derivatives, polyparaphenylene vinylene and its derivatives, polythiophenvinylene and its derivatives , Oligothiophenes of alpha-5-thiophene and derivatives thereof, phthalocyanine and derivatives thereof with or without metal, naphthalene tetracarboxylic diimides and derivatives thereof, poly Preparation of thin film transistor (TFT) by spray printing method, characterized in that selected from phenylene tetracarboxylic diimide-polythiophene copolymer and its derivatives (poly (perylene tetracarboxylic diimide) -co- (thiophene)) How to. 6. The method of claim 5,
The metal oxide coating liquid is zinc oxide, indium tin oxide, tin oxide, zinc tin oxide, indium gallium zinc oxide oxide, characterized in that the method for manufacturing a thin film transistor (TFT) through a spray printing method. 6. The method of claim 5,
The polymer insulator coating liquid is Al2O3, Ta2O5, BST, PZT method for manufacturing a thin film transistor (TFT) through a spray printing method, characterized in that selected from the solution dispersed. 6. The method of claim 5,
The polymer insulator coating liquid may be polymethacrylate (PMMA, polymethylmethacrylate), polystyrene (PS, polystyrene), phenolic polymer, acrylic polymer, imide polymer such as polyimide, arylether polymer, amide polymer, fluorine polymer, p -A method of manufacturing a thin film transistor (TFT) through a spray printing method, characterized in that selected from xyrene-based polymer, vinyl alcohol-based polymer, parylene (parylene).
Organic thin film transistor manufactured by spray printing method. Metal Oxide Transistors Fabricated by Spray Printing Carbon Nanotube Transistors Fabricated by Spray Printing Graphene Transistors Fabricated by Spray Printing The method according to claim 10, wherein
The transistor is characterized in that the bottom-gate form The method according to claim 10, wherein
The transistor has a top-gate shape
A substrate on which the substrate is positioned;
A take-up roll and a take-up roll for continuously moving the substrate;
A roller for maintaining a constant tension and speed of the substrate;
Roll-to-roll coating apparatus for manufacturing a TFT, characterized in that consisting of a spray coating for spraying the coating liquid on the substrate located on the base portion 17. The method of claim 16,
Roll-to-roll coating apparatus for manufacturing a TFT, characterized in that two or more spray coating unit is installed Positioning the substrate on top of the substrate;
Connecting both ends of the substrate to a take-up roll and a take-up roll;
Continuously moving using a roller while maintaining a constant tension and speed of the substrate portion connected to the take-up roll and the take-up roll;
Spraying a coating solution from a spray coating part on a substrate positioned above the continuously moving substrate part;
Method for continuously manufacturing a TFT by the roll-to-roll coating method characterized in that consisting of

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